Stratolaunch's website now reveals that the company has reinvented itself as a builder, tester and operator of hypersonic vehicles — those that can travel at least five times the speed of sound, or Mach 5. The huge plane is key to this new mission, hauling vehicles aloft to test various payloads in the extreme environments imposed by hypersonic flight. Those vehicles will include Stratolaunch's Talon-A, a 28-foot-long (8.5 m), 6,000-lb. (2,722 kilograms) reusable craft capable of reaching Mach 6. The huge dual-fuselage plane — which used to be called Roc, but is now apparently known as the Stratolaunch Carrier —...